FTIR Analysis of MoPrP Fibrils

MoPrP fibril samples were dialyzed into MilliQ water for 24 hours at 4 °C, then fibrils were separated from buffer solution by centrifugation at 20 000 x g for 30 min and resuspended in 1 mL of D₂O, the centrifugation-resuspension procedure was repeated three times. All samples were then sonicated for 60 s (MS-72 tip, 20% sonication strength). The FTIR spectra were recorded as described previously^{44 (link)} using Bruker Vertex 80 v IR spectrometer equipped with mercury cadmium telluride (MCT) detector. For all measurements, CaF₂ transmission windows and 0.05 mm Teflon spacers were used. Spectra were recorded at room temperature under near-vacuum conditions (~2 mBar). For each spectrum, 256 interferograms of 2 cm⁻¹ resolution were co-added. A D₂O spectrum was subtracted from each sample spectrum. All the spectra were normalized to the same area of amide I/I′ band (1700–1595 cm⁻¹). All data processing was performed using GRAMS software.